We have owned many JD's over the years, and currently have 7 of them ranging from a 6220 to a 8320, along with a couple of blue ones, :ashamed:. For 160 acres, you will not need anything larger than a 100HP tractor. In fact another family farm down the road farms about 1000 acres of land and they have nothing larger than a 2955 2WD which I think were about 90-95 HP.
A 100 HP 4WD tractor will easily pull a 5 furrow plough, we have a 6 furrow reversible and I sometimes use the 7220, 105 HP to do so (a big pull mind you). That being said I wouldn't want to go much smaller than 100 HP as I find many implements, especially those PTO driven require it. For example, there is a huge difference in cutting hay with the 6220 as opposed to the 7220. But again ... the 6220 does do the job, just much slower.
Have you ever thought about buying used? this would allow you to get into a better model at a much better price. It may also allow you to pick up a larger tractor such as a 100 Hp and then a smaller loader tractor for example (our farm doesn't function without a loader tractor, or two!).
Just my $0.02